1. Field of the Invention
The present invention relates to a lever hoist for use in raising, lowering or dragging objects to be transferred by repeatedly rocking a lever of the hoist.
2. Description of the Prior Art
Lever-operated small type hoisting and dragging devices have been known. One of these devices includes an elastic resistance member interposed between a driving member and a driven member for releasing a braking assembly, and an operating lever rockable about the driving member. The operating lever includes a change pawl metal pivotally secured thereto having winding-up and winding-off driving pawls detachably engageable with a change gear on the driving member for respectively driving the change gear in winding-up and winding-off directions and engagement portions for respectively holding the winding-up and winding-off directions. The operating lever is further provided with a holding member adapted to be detachably engaged with the engagement portions of the change pawl metal by means of an engagement spring. With such a device, urging forces of the pawls engaged with the change gear are substantially equal to each other.
With the known device, if the urging force of the winding-up driving pawl acting upon the change gear by the action of the engagement spring is too large, the change gear and hence the driving member are returned by a return movement of the operating lever for a next driving movement when a light load is hoisting by the device. Accordingly, such a device cannot hoist a light load. On the other hand, when a light load is lowering by the device, the urging force of the winding-off driving pawl acting upon the change gear by the engagement spring is too small, the change gear overcomes the weak urging force so as to be rotated by a gravity force of the load, because such a light load does not operate the braking assembly. Frequently, the known device cannot therefore lower a light load.